Integrated Waste Water Treatment – A Case Study

Introduction

In India, more than 80% of the water supply to the ecosystem is waste which is responsible for severe health hazards, it is mainly due to improper wastewater management. Industries and large cities are important reasons for wastewater. In 2016, Renve of INR 24 billion were last in five months which is nearly 7 billion units of coal. It is due to scarcity of water. The main motto of wastewater management is to keep the water clean and safe. Through this process, the water can be used for all purposes like drinking, washing, and commercial purposes. There are two sources of wastewater.

(i) Point source

(ii) Non-point source

The way of treating the wastewater and sewage plant in an integrated manner by both two process

(i) Natural ways

(ii) Artificial manner

(i) Conventional sedimentation includes filtering and chlorinating the water where more harmful materials and heavy metals have been removed.

(ii)Many marshes, algae, fungus, seaweed, and over 6 connected meshes are brought by the biologists for 60 hectares to neutralise the water naturally.

• Marshes also help grow marine life such as fishes, animals, and birds
• FOAM – Friends of Arcata Marsh took care of this wastewater management. It is one of the biggest steps in safeguarding nature
• Ecological sanitation is practical hygiene, cost-efficient method for excreting human waste by dry compost toilets. It is one of the nutrient-rich fertilisers for plants
• This project is also started in Kerala and Srilanka under the name of EcoSan

Wastewater Treatment Plant

• In this process, all the contaminants present in the wastewater are removed, making them sustainable for usage. Make kind of wastewater is treated in this phase like domestic, industrial, agricultural, sewage, and leachate

Sludge is considered the end product of this waste treatment plant. Processes include sedimentation, polishing, and oxidation. The recycled water from the plant is known as reclaimed water.

Types of Wastewater Treatment Plant

Based on the type of contamination the treatment plant includes

1. Industrial wastewater treatment plants
2. An agricultural wastewater treatment plant
3. Leachate treatment plant
4. Sewage treatment plant

In industrial treatment plant

• In this process, unwanted products are treated and recycled into the water cycle
• Many industries like petrochemical plants and refineries have their treatment plant as they have many toxic materials, oil, grease as the by-products
• To prevent pollution, industries set up wastewater treatment plants and reuse the same water for manufacturing purposes.
• In industrial processes, brine treatment removes solids, organic acids, alkaline, grease, oil and toxic pollutants

Agricultural Wastewater Treatment Plant

• In this process, the wastewater that comes from the animal and plant operation is removed
• The recycled water is again used for milk and egg production
• Sometimes it may be disposed of with the help of a sprayer and trickles
• Runoff from the agricultural land contains pesticides, fertilisers, animal slurry, plant residue, animal residues. It can be removed in this process

Leachate Treatment Plant

In this process, leachate water is treated from landfills. The processes involved in this treatment are

• Biological treatment
• Mechanical treatment
• Treatment with active carbon filters
• Electrocoagulation
• reverse osmosis using disc tube

Sewage Treatment Plant

• It is one of the steps to avoid water pollution
• The sewage treatment plant is one of the integrated wastewater treatment
• In this treatment, all the sewage waste from domestic, pre-treated industrial, and the company are treated to remove the harmful metal and make it suitable for the environment
• There are different varieties of sewage plants is available like

1. Decentralised system(On-site treatment system)
2. Large centralised system (connection of large network of pipe)

• There are two stages in Sewage treatment

1. Primary treatment
2. Secondary treatment – here, organic matter is reduced by aerobic and anaerobic process
3. Tertiary treatment – advanced treatment where nutrients can be removed

• Many sewage treatment plants are built based on biological aspects by considering the quantitative and qualitative aspects
• In rural areas, on-site sanitation is followed that includes a septic tank, OSS (on-site sewage system), vermifilters, and drain fields
• In some countries, even the fourth treatment stage is followed to remove micro pollution
• Sanitation is one of the parts of the sewage treatment plant to treat solid waste, human waste, and drainage waste
• STP- sewage treatment plant for sewage works. WWTP – wastewater treatment for the treatment of industrial wastewater
• The main objective of the sewage treatment plant is to degrade all the biodegradable components, including organic matter and remove nutrients, pathogens, micro pollutants and make them suitable for the environment.
• Even sewage sludge is also treated before its use. It is divided into biosolids and fertilisers

Types of Sewage Treatment Processes Available

As we saw above, there are two processes is conducted

1. Decentralised system (On-site treatment system)
2. Large centralised system (connection of large network of pipe)

Many technologies are available in sewage treatment like high cost, low-cost options, intensive, extensive, mechanised system, and natural-based system

Mainly there are two types of processes

(i) Low tech, extensive or nature-based processes

(ii) High tech, intensive, or mechanised processes

Low tech, extensive or nature-based processes

• In this case, little or no energy is required
• For example, toilet wastewater is provided with a septic tank for pre-treatment.
• Nature-based treatment plants take place in urban and rural areas.
• This type of sewage treatment plant is one of the integrated wastewater treatment plants based on the natural treatment process
• One of the best examples of the natural-based low-cost treatment plant is Waste stabilisation ponds. One can avoid operation and maintenance costs.

High tech, intensive, or mechanised processes

Here the sewage treatment is a bit expensive. As the maintenance and operation costs are high. High effluent quality is available in the mechanised process. Here are some of the systems and processes available in the mechanised process are

1. Activated sludge system
2. Reverse osmosis
3. Filtration
4. Membrane bioreactor
5. Extended aeration
6. Aerobic treatment system

Sewage Treatment Process

Different types of sewage processes are available in sewage treatment. Here are listed below.

1. Preliminary treatment
2. Primary treatment
3. Secondary treatment
4. Tertiary treatment

Preliminary treatment

In this process, all the coarse material that can block or clog the pipe is removed. Some of the steps followed in the preliminary treatment are

1. Screening
2. Grit removal
3. Flow equalisation Fat and grease removal

Primary treatment

In this process suspended, and the organic matter is removed. Here

• 50 – 70% of the suspended solids
• 25-40% of BOD (biological oxygen demand) is removed.

Secondary treatment

Here a biological digester is installed to remove the organic matter and solid particles, toxic materials are removed as much as possible. Many micrograms grow on it and form flocs. These flocs remain on the sludge and reduce the concentration of the pollutants.

Tertiary treatment

In this process nutrients, micro-pollutants are removed. More than one process is performed in the tertiary treatment.

Conclusion

Many health hazards can occur due to not responsibly managing wastewater. Wastewater management aims to keep the water clean and safe. Through this process, the water can be used for all purposes like drinking, washing, and commercial purposes. Based on the type of contamination the treatment plant includes -Industrial wastewater treatment plants, agricultural wastewater treatment plants, Leachate treatment plants, and Sewage treatment plants.